The present application relates to a battery system in which 2 or more unit cells are electrically connected in series, particularly to a battery system suitable for a fuel cell, a solar cell and the like.
In the case where a battery is used as a power source, it is often the case that a necessary quantity of unit cells is connected in series to obtain a high voltage in order to obtain a voltage necessary for a load. In particular, in a fuel cell or a solar cell, the electric power generation voltage per unit cell is low. Thus, it is general that a plurality of unit cells (electric power generation parts) are connected in series to configure a battery system.